This invention relates to apparatus and method for patching and/or switching multiple-wire electrical interfaces, and especially to such apparatus in which mere insertion of a plug member not only makes a desired connection to a first set of conductors but also temporarily breaks a pre-existing connection of the first set of conductors to a second set of conductors.
There are many important applications, particularly in the communications field, in which it is necessary to open a normal connection between a first set of one or more conductors and a second set of corresponding conductors, and to connect one or both of said sets instead to a third corresponding set of conductors. For example, in telephone and telegraphs systems it has long been common practice to terminate a large number of communications lines, each for example consisting of two or four wires, in corresponding large arrays of receptacles or jacks. These receptacles or jacks have often included not only means for making quick connection to, and disconnection from, the wires of a particular line by the insertion of an appropriate plug into the corresponding jack but typically also include means establishing a normal connection between wires of that line and wires of another line through switch contact associated with and integral to each of the jacks, which normal connection is automatically interrupted when the plug is inserted. Thus the jacks and their contacts, as well as the plug, conventionally are designed and arranged in such a way that when a so-called "patch cord" plug is inserted into a jack, the switch contacts of the jack are thereby moved to interrupt the normal connection and to transfer the connection through the plug to the patch cord. By such means it is possible, by simple insertion of the plug, not only to interrupt an existing connection, but to transfer that connection to whatever equipment or communications line may be connected to the other end of the patch cord.
With such arrangements it is easy to use the patch cord to rearrange the interconnections of communications lines, to disconnect and reconnect various communications devices associated with those lines, and in general to facilitate diagnosis of faults, performing of tests, making of electrical measurements, substituting of good lines for bad, and restoring of service in case of service outage. Systems embodying such jack fields and plug arrangements are generally referred to as technical control systems, or, for short, tech control systems. Such systems have typically been found in large telephone or telegraph central stations, where high concentrations of communications channels exist.
Difficulties with such conventional approaches increase markedly when the number of wires in the communications lines increase beyond a few. Thus while it has been possible to operate in this manner on lines containing several wires by appropriate design of plug and jack, and while it is possible to bond together a number of plugs to be inserted into a small physical array of adjacent jackes to accomplish similar purposes, as the number of wires involved increases substantially, for example up to 12, 24, or even more wires, problems of increasing bulk, decreasing reliability and increasing cost have made this conventional approach infeasible.
However, in recent years the desirability of such a patching and switching capability for communications lines containing large numbers of wires has become apparent. For example, particularly with the advent of data communications systems operating in conjunction with computers, it has become common to find a number of communications lines terminating on the premises of end-users where one or more computers or other type of local equipment may be in use. Such local equipment is usually connected to the communications lines through modems which convert signals emanating from the local equipment into a form suited to transmission over the communications lines, and vice versa. The connection between such modems and the local equipment is typically made through many-wired lines. Although the number of communications lines at an end-user site is typically smaller than the number of lines at a telephone or telegraph central station, there is just as great a need for flexibility in diagnosis, repair, and restoration of service. In such situations the capability of providing a patching facility for many-wired lines becomes important.
One particular application in connection with which the invention will be specifically described in the interest of definiteness, is one in which coded audio-frequency tone signals are transmitted over several public carrier lines such as telephone lines, to end-user premises, where a modem converts the audio signals on each communication line into digital electrical signals on a corresponding many-wired line for delivery to a local equipment such as a corresponding computer. For example, at a given end-user site there may be a plurality of computers or other local equipment, and/or a plurality of modems including some spare modems not ordinarily in use. The many-wired lines (e.g. 24 wires) which connect each modem with its corresponding local equipment may then be brought out to corresponding front receptacles on a technical control system, so that they can be monitored by plugging into the appropriate receptacle. However, in addition it is often desirable to perform switching and patching functions to change which local equipment is connected to which modem, to bypass a possible faulty modem and replace it with a spare modem, or for any of many other similar functions.
One approach which has been used to provide such a patching function for many-wired lines involves connecting the wires from a given modem to the wires leading to a corresponding local equipment by way of normally-closed switch contacts within the technical control system; connecting the line on the modem side of the switch and the line on the local equipment side of the switch to contacts at corresponding front receptacles in the tech control system where contact to them can be made by suitable corresponding plugs; and providing a shaft extending through the front panel of the tech control system which can be rotated by an operator between a "normal" position in which the internal switch contacts are closed so as to interconnect modem and local equipment internally, and a "patch" position in which the latter connections are broken and a patch cord may be used to connect the contacts at either of the two front receptacles to any other receptacle to accomplish any type of switching or monitoring operation which is desired. This arrangement not only requires a relatively costly multiple-contact manually operable switching arrangement, but in addition requires that the operator performing the patching function himself execute a further necessary operation before he can accomplish patching, namely the turning of the control to the patching position. This not only requires additional effort, but may result in improper connections in the event that the operator should forget to turn the switch to the appropriate position.
The only other available method known by applicant for performing such a function for many-wired lines involves a method practiced by Cooke Engineering Company, a division of Dynatech Laboratories, Inc., of Virginia. It involves the use of normally-closed sets of contacts within a receptacle, and a relatively long wand having a number of contacts arranged linearly along it. The internal normally-closed contacts are arranged in a correspondingly-linear arrangement along the receptacle, into which receptacle the wand is inserted endwise and then rotated about its longitudinal axis. This establishes electrical connection between the contacts on the wand and the contacts within the receptacle, while at the same time opening the internal normally-closed contacts. However, this arrangement has not been found practical with more than about 16 wires, and in addition requires that the user not only insert the wand but also turn it in order to obtain the desired objective.
Accordingly, it is an object of the invention to provide new and improved apparatus and method for controlling the connection of a first plurality of wires to a second plurality of wires.
Another object is to provide such method and apparatus which provides controlled connection of said first plurality of wires to said second plurality of wires and to a third plurality of wires.
A further object is to provide such apparatus and method in which connection of said third plurality of wires to said first plurality of said wires automatically disconnects said second plurality of wires from said first plurality of wires.
Another object is to provide such method and apparatus which are relatively easy to manufacture and relatively inexpensive as well as reliable.
Still another object is to provide an improved method and apparatus for providing a patching capability for many-wired lines, and which is particularly simple to operate and use.